#!/usr/bin/env python

# Copyright 2012 Google Inc. All Rights Reserved.
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
#    http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.

"""Checks whether the request has the required content type header set."""

import logging
import http

__author__ = 'Maciej Machulak'
__maintainer__ = 'Maciej Machulak'
__email__ = 'mmachulak@google.com'

__copyright__ = 'Copyright 2012, Google Inc.'
__license__ = 'Apache License 2.0'
__version__ = '0.2'
__status__ = 'Prototype'


def accept_content(content_type):

  def inner_accept_content(handler):

    def check_content(self, *args):
      logging.debug('required content type: %s', content_type)
      header = self.request.headers.get(http.Header.content_type)
      invalid_code = _is_invalid_content_type(content_type, header)
      if invalid_code:
        self.response.set_status(invalid_code)
        return
      handler(self, *args)

    return check_content

  return inner_accept_content

def _is_invalid_content_type(requested, header):
  """Return the error code or Null if everything is OK."""

  if not header:
    logging.info('request does not have the content type header')
    return 400
  header = header.lower()
  header = header.split(';')[0]
  if requested != header:
    logging.debug(
        'request does not have the required content type header:'\
        ' %s', header)
    return 415
  return None